From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 935F1C3DA4A for ; Fri, 16 Aug 2024 09:41:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 19A628D005F; Fri, 16 Aug 2024 05:41:21 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 1498F8D0002; Fri, 16 Aug 2024 05:41:21 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 011088D005F; Fri, 16 Aug 2024 05:41:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id D774A8D0002 for ; Fri, 16 Aug 2024 05:41:20 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 8C2D8807C5 for ; Fri, 16 Aug 2024 09:41:20 +0000 (UTC) X-FDA: 82457615520.20.BC75EEA Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by imf13.hostedemail.com (Postfix) with ESMTP id 9767D2000F for ; Fri, 16 Aug 2024 09:41:17 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of jonathan.cameron@huawei.com designates 185.176.79.56 as permitted sender) smtp.mailfrom=jonathan.cameron@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1723801204; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=S9YKefZY3A6Uq+6/rTqeRu8WmLOMkTVImh7mybq7Zj8=; b=ItLKFX9One/afcwtdrBzOw67GDteM94Sw91NuspPXp/YCW9Oer/nnsvRtV9SucxQZNB5O+ 5IR6bmKrJ8LhtRmqvwTQbDDrTLDcTJUAxP6yYv33nViBWcGixTZC05naREoFzRsqQA9zzc qUP1Kf1Bgkk0bbAk/9TigQnfHY/HwiU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1723801204; a=rsa-sha256; cv=none; b=gd++tHFGSGewnb7Cmg00Ee4j40xKY1AY0IbX9jeYFbUx6T5qAIh2BYoMxg88Zpb75CnWe1 j+t0rb8stgjiDbgZPyRPcv8PS9YBJhjm8Nx2U0det7T3VyHfq9t791rFAnWCTFZ1ERHInT IvhzB0fQPo6DUlMnTcswgt3roLqJ9pA= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=none; spf=pass (imf13.hostedemail.com: domain of jonathan.cameron@huawei.com designates 185.176.79.56 as permitted sender) smtp.mailfrom=jonathan.cameron@huawei.com; dmarc=pass (policy=quarantine) header.from=huawei.com Received: from mail.maildlp.com (unknown [172.18.186.216]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4WlcPJ4psFz6K5l3; Fri, 16 Aug 2024 17:38:28 +0800 (CST) Received: from lhrpeml500005.china.huawei.com (unknown [7.191.163.240]) by mail.maildlp.com (Postfix) with ESMTPS id 2AACD1400DB; Fri, 16 Aug 2024 17:41:12 +0800 (CST) Received: from localhost (10.203.177.66) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.1.2507.39; Fri, 16 Aug 2024 10:41:11 +0100 Date: Fri, 16 Aug 2024 10:41:10 +0100 From: Jonathan Cameron To: Hannes Reinecke CC: David Hildenbrand , , , Davidlohr Bueso , Ira Weiny , John Groves , , Oscar Salvador , , Dave Jiang , Dan Williams , , , John Groves , Fan Ni , Navneet Singh , " =?UTF-8?Q?=E2=80=9CMichael?= S. =?UTF-8?Q?Tsirkin=E2=80=9D?=" , Igor Mammedov , Philippe =?UTF-8?Q?Mathieu-Daud=C3=A9?= Subject: Re: [RFC] Virtualizing tagged disaggregated memory capacity (app specific, multi host shared) Message-ID: <20240816104110.000012e6@Huawei.com> In-Reply-To: <904a433c-0471-4f11-a34b-cef8adf1663c@suse.de> References: <20240815172223.00001ca7@Huawei.com> <904a433c-0471-4f11-a34b-cef8adf1663c@suse.de> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.203.177.66] X-ClientProxiedBy: lhrpeml500003.china.huawei.com (7.191.162.67) To lhrpeml500005.china.huawei.com (7.191.163.240) X-Stat-Signature: smzu3s8ano97u75w7cqztf7exywoy46e X-Rspamd-Queue-Id: 9767D2000F X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1723801277-251939 X-HE-Meta: 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 z2AIQUFl VY9O9oGZp7/5CHg0wSeFfGDTqNQt/yuMj6aIsDkV014chI5vjRAVwhQa84xN6SdcJGEFu4orEUkKKiyiYYhhh2p/g/HFhs8lRAv7HbyLshqag232pDV3VnSKRnCDzWyg6hYI5XYduPAWpZv8WU/ww1z1SpR6Cd+Pqtrfjrvnsaf8N2TngHkwNlXUtCeBJ1UShc8kYWNILUDmzimk= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 16 Aug 2024 09:05:46 +0200 Hannes Reinecke wrote: > On 8/15/24 18:22, Jonathan Cameron wrote: > > Introduction > > ============ > > > > If we think application specific memory (including inter-host shared memory) is > > a thing, it will also be a thing people want to use with virtual machines, > > potentially nested. So how do we present it at the Host to VM boundary? > > > > This RFC is perhaps premature given we haven't yet merged upstream support for > > the bare metal case. However I'd like to get the discussion going given we've > > touched briefly on this in a number of CXL sync calls and it is clear no one is > > entirely sure what direction make sense. We may briefly touch on this in the > > LPC CXL uconf, but time will be very limited. > > > Thanks for the detailed write-up. > > Can't we have an ad-hoc meeting at OSS/LPC to gather interested/relevant > people to explore ideas around this? Absolutely. If people want to email me directly (or mention in the thread) I'll gather up a list of people to try and find a suitable time / place (and then post that here). > > In particular I'd be interested on how to _get_ the application specific > memory to the application in question. It's easy if you have your own > application and design it to work on DAX devices. Obviously this > approach won't work for unmodified applications; however, they really > might want to use this, too. That's a good parallel question (as not virtualization specific). I'd be tempted to enable this path first for aware applications, but longer term the ability to use this via common allocator libraries (LD_PRELOAD etc) might make sense (or some other path?) > > And, of course, the other mentioned problems are worth discussing, and I > do agree that the uconf will probably not providing sufficient time for > this. > > Cheers, > > Hannes